Key instruments will be turned off to save power as Martian winter looms

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This artist rendition provided by NASA and the Jet Propulsion Laboratory shows the Phoenix lander on the arctic plains of Mars digging a trench through the upper soil layer. After five months, NASA is shutting down key instruments aboard the Phoenix spacecraft to conserve power.

LOS ANGELES — After five months of digging in the Martian soil, NASA is shutting down key instruments aboard the Phoenix spacecraft to conserve power.

Phoenix landed in May to study whether the arctic environment could support primitive life. The lander has been struggling to survive with fewer hours of sunlight reaching its solar panels.

NASA decided to gradually shut down the spacecraft's instruments in hopes of getting several more weeks of scientific study.

Engineers on Tuesday sent commands to disable a heater that warms the spacecraft's robotic arm and oven instrument, a move that will save about 250 watt-hours of power a day. Three other heaters that power other spacecraft electronics will be shut down over the next several weeks.

The lander has recorded snowfall, scraped up ice and found that the dust on the surface of Mars chemically resembles seawater, adding to evidence that liquid water that may have supported life once flowed on the planet's surface.

"As expected, with the Martian northern hemisphere shifting from summer to fall, the lander is generating less power due to shorter days and fewer hours of sunlight reaching its solar panels," NASA explained in a statement.

"If we did nothing, it wouldn't be long before the power needed to operate the spacecraft would exceed the amount of power it generates on a daily basis," said Phoenix project manager Barry Goldstein of NASA's Jet Propulsion Laboratory. "By turning off some heaters and instruments, we can extend the life of the lander by several weeks and still conduct some science."

The Phoenix team has left a thermal and electrical-conductivity probe thrust into the soil to measure temperature, humidity and conductivity. The probe does not need a heater and should continue to send back data for weeks.

This report includes information from The Associated Press and Reuters.